A Bis(pyridine N‐oxide) Analogue of DOTA: Relaxometric Properties of the GdIII Complex and Efficient Sensitization of Visible and NIR‐Emitting Lanthanide(III) Cations Including PrIII and HoIII

摘要: We report the synthesis of a cyclen-based ligand (4,10-bis[(1-oxidopyridin-2-yl)methyl]-1,4,7,10-tetraazacyclododecane-1,7-diacetic acid=L1) containing two acetate and 2-methylpyridine N-oxide arms anchored on nitrogen atoms cyclen platform, which has been designed for stable complexation lanthanide(III) ions in aqueous solution. Relaxometric studies suggest that thermodynamic stability kinetic inertness Gd(III) complex may be sufficient biological applications. A detailed structural study complexes by (1) H NMR spectroscopy DFT calculations indicates they adopt an anti-Δ(λλλλ) conformation solution, is, anti-square antiprismatic (anti-SAP) isomeric form, as demonstrated analysis paramagnetic shifts induced Yb(III) . The water-exchange rate is ${k{{298\hfill \atop {\rm ex}\hfill}}}$=6.7×10(6)  s(-1) , about quarter mono-oxidopyridine analogue, but still 50 % higher than ex}\hfill}}}$ GdDOTA (DOTA=1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid). chromophores can used to sensitize wide range Ln(III) emitting both visible (Eu(III) Tb(III) ) NIR (Pr(III) Nd(III) Ho(III) spectral regions. emission quantum yield determined (${Q{{{\rm L}\hfill Yb}\hfill}}}$=7.3(1)×10(-3) among highest ever reported this metal ion sensitization ability ligand, together with spectroscopic relaxometric properties its complexes, constitute useful step forward way efficient dual probes optical imaging (OI) MRI.